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[Example-Lab] Modifying the Attributes of the Embedded Class from Embedding Class in Hibernate 5

There might be situations where you would want to modify the attributes of the embedded class (eg. Address) within an embedding class (eg. User), for instance, changing the database column name for a field.

We can use @AttributeOverride annotation to override the details of a field of the embedded class and then enclose all such @AttributeOverride annotations inside @AttributeOverrides annotation.

[Example-Lab] Embedding Value Types Within an Entity Class in Hibernate 5

A value type is a type which doesn't have existence of its own, but belongs to an entity, like an user and his address. Value types are always completely owned by their containing entity.

We will embed an Address class inside a User class. The simplest way to embed a value type in an entity class is to treat the member variables of the embedded class (e.g. Address), the same way as we treat the member variables of the embedding class (e.g. User) by adding more columns to the entity table one column each for the value type class members

Embedding Value Types and Collections Within an Entity Class in Hibernate 5

We have already seen the definition and properties of an entity and value class in http://javajee.com/entities-and-value-types-in-hibernate-43. We will not see how we can actually embed a value type within an entity. We will also see how we can embed a collection inside an entity.

 

Entities and Value Types in Hibernate 5

An entity is a type on its own and has an existence of its own (e.g. Course, User etc.).

A value type is a type which doesn't have existence of its own, but belongs to an entity (e.g. Address of an User). Value types are always completely owned by their containing entity.

 

Defining entities and value types in Hibernate

@Entity annotation (javax.persistence.Entity) over the class tell hibernate to treat this class as our entity class that needs to be saved.

Most Common Annotations Used in Hibernate 5

Here we will discuss most commonly used basic annotations in hibernate - @Entity, @Table, @Id, @GeneratedValue, @Column, @Basic, @Transient, @Temporal and @Lob. Even though many annotations has both JPA (java.persistance) and hibernate (org.hibernate) versions, it is preferred to use JPA annotations whenever possible. As you can see below, some of the hibernate specific annotations are already deprecated.

 

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